Why Build Your Own Certificate Authority

• Introduction
• Use Cases for Certificate-Based Authentication
• Self-Signed vs. Public CAs
  • Self-Signed Certificates
  • Public Certificate Authorities
• The Better Alternative: Build Your Own CA
• Two-Tier CA Hierarchy
• My Real-World Case
• What’s Next?

Introduction

Managing a large number of users or devices in an organization - or even a home lab - introduces several challenges:

• Data security and privacy
• Establishing trust between systems
• Ensuring integrity of data and systems
• Automating access and lifecycle management
• Providing phishing-resistant authentication

Use Cases for Certificate-Based Authentication

CA (Certificate Authority) can be used for securing many kinds of infrastructure, such as:

• Securing web servers (HTTPS)
• VPN authentication
• Email encryption (S/MIME)
• IoT device identity
• Cloud services and API trust
• Mutual TLS (mTLS) authentication

Self-Signed vs. Public CAs

When evaluating certificate options, you may consider self-signed certificates or public Certificate Authorities (CAs). However:

Self-Signed Certificates

• Not trusted by browsers or operating systems by default
• Difficult to distribute and manage in large environments

Public Certificate Authorities

• Can be expensive for many certificates
• Offer limited control over certificate lifecycle or policy

The Better Alternative: Build Your Own CA

By building your own Certificate Authority using tools like Easy-RSA, you gain:

• Complete control over your PKI
• Zero cost per certificate
• Ability to define your own trust policies and usage

Easy-RSA is a simple yet powerful command-line utility to manage your own Public Key Infrastructure (PKI).

This gives you total control, zero recurring cost, and the ability to build a trust model that suits your environment.

Two-Tier CA Hierarchy

A best practice is to create:

• Root CA: Offline, used only to sign Intermediate CA
• Intermediate CA: Actively issues end-entity certificates

🔐 Keep the Root CA offline to minimize security risks.

Only use it when necessary to sign or revoke Intermediate CAs.

graph TD
    RootCA["🛡️ Root CA (Offline) - Signs Intermediate CA"]
    CRLRoot["📄 Root CRL (Exported)"]
    IntermediateCA["🔄 Intermediate CA (Online) - Signs End-Entity Certs"]
    CRLInt["📄 Intermediate CRL"]
    WebServer["🌐 Web Server"]
    EmailCert["📧 Email Client"]
    VPNCert["🔐 VPN Device"]

    RootCA -->|Sign| IntermediateCA
    RootCA -->|Publish| CRLRoot
    IntermediateCA -->|Publish| CRLInt
    IntermediateCA -->|Issue| WebServer
    IntermediateCA -->|Issue| EmailCert
    IntermediateCA -->|Issue| VPNCert

My Real-World Case

Let me share a bit of context. In my home lab, I manage:

• OpenVPN servers
• Microsoft 365 identity integrations
• Internal web applications
• Secure email with S/MIME

Each time I added a new device or user, managing credentials was painful. Building a CA infrastructure simplified trust, reduced manual effort, and enabled automation.

What’s Next?

In Part 2, I’ll walk you through the exact steps I used to build a Root CA, an Intermediate CA, and generate certificates with Easy-RSA.

Stay tuned!